Tube bending mandrel



United States Patent 01 fice 3,415,107 TUBE BENDING MANDREL Oronzo J. Ruscitti, Melrose Park, Ill., assignor to Pines Engineering Co., Inc., Aurora, Ill., a corporation of Illinois Filed June 15, 1966, Ser. No. 557,822 Claims. (Cl. 72-466) I ABSTRACT OF THE DISCLOSURE A flexible mandrel comprised of a series of ring members arranged on a series of links and wherein a first and third member only is connected to first and third links of the series.

This invention relates to improvements in flexible mandrels for use in bending tubular stock, and more particularly to the novel construction and assembly of such a mandrel.

An object of the invention is to provide a flexible mandrel of such construction as to be flexible in one plane only while permitting the ring members thereof to rotate freely and thus present new wear surfaces while in use.

Another object is to provide novel linkage joining the ring members of a flexible mandrel.

A further object is to provide a flexible mandrel assembly which is not difficult to manufacture and which can easily and quickly be assembled or disassemble-d.

A still further object is to provide a rugged flexible mandrel comprised of a series of link-connected ring members which can easily be aligned in straight axial relation but capable of readjustment to adapt them to bends of various degrees.

The structure by means of which the above noted and other objects and advantages of the invention are attained will be described in the following specification, taken in conjunction with the accompanying drawings, showing a preferred illustrative embodiment of the invention, in which:

FIG. 1 is an elevational view of a tube bending mandrel embodying the features of the invention;

FIG. 2 is an enlarged longitudinal sectional view of the mandrel, viewed in the same plane as in FIG. 1; and,

FIG. 3 is another longitudinal sectional view of the mandrel viewed at right angles to the FIG. 2 illustration.

Referring to the exemplary disclosure of the mandrel shown in the accompanying drawings, and particularly to FIG. 1, the tube bending mandrel includes a straight rigid mandrel section 11 and a flexible mandrel section 12. The straight rigid section 11 is comprised of a shank 13 having a threaded opening 14 at one end to receive the usual stem 15 that is connected to a hydraulic piston-cylinder assembly, not shown. The other end of said shank 13 is counterbored, as at 16, to receive a rod 17 with functions as means to connect the flexible section 12 to the said shank. As shown, a transverse bore 18 intersects the counterbore 16 to receive an anchor pin 19 that also extends through rod 17 for holding the rod in a fixed position in said shank. The outer end of said rod 17 is suitably cut away to provide a flat faced nose 20 which has a transverse aperture 21 therein.

The flexible mandrel section is comprised essentially of a series of like ring members 22 of ball-like configuration. As shown, each of these members has a spherical outer surface 23 and a relatively thick wall of limited length.

The lower disposed end of each ring member has a concave annular inner surface 24 complementary to the spherical outer surface 23 of an adjacent ring member. Said inner surface 24 terminates in a central bore 25. The other end of said ring member 22 is formed with a cup-shaped recess 26 that terminates in a bore enlargement 27 defining an annular internal shoulder or seat 28.

These ring members 22 are interconnected by a series of links that extend through the bores 25. Referring specifically to FIG. 3, a pair of spaced apart links 29 are connected, as by a pin 31, to the flat faced nose 20 of rod 17. The upper or free ends of these links have a semicircular head or flange 32 that is seated on the annular seat 28 of a first ring member 22. Iournalled, as by a pin 33, between the pair of links 29 is one end of a single link 34, the other end of which is pivotally connected, as at 35, between the lower ends of a second pair of links 29a. A second ring member 22a is fitted over these links, loosely, and a third ring member 22b is fitted over the upper ends of said pair of links 29a. The links of this second pair of links 29a each have a semi-circular head 32a that bears against annular seat 28a of the third ring member 22b for retaining the assembly together. Said semi-circular heads 32a are held spaced apart and seated by a single link 34a arranged between them and pivoted to them as by pin 36.

The links 29, 34, 29a and 34a each are recessed on one common edge, as at 37, to allow the ring members to become displaced angularly in one common direction only so as to follow the bend in a tube when the mandrel is inserted thereinto. Because of the pivotal link assemblage and the fact that the other side edges of the links are not recessed, the ring members 22 can be displaced in one direction only, any stresses applied in other directions serving to retain the ring members in axial alignment for the purpose of assisting initial insertion of the mandrel into a tube.

Although I have described a preferred embodiment of the invention, in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather than restrictive, as many details of the structure may be modified or changed without departing from the spirit or scope of the invention. Accordingly, I do not desire to be restricted to the exact construction described.

I claim:

1. A flexible mandrel comprising, a shank portion, first link means pivotally connected at one end to said shank portion, a first ring member telescoped over said first link means, means on said first link means to engage with the first ring member, a second link means pivotally connected at one end to said first link means, a second ring member telescoped over said second link means, a third link means pivotally connected to the second link means, a third ring member telescoped over the third link means, means on the third link means engageable with the third ring member to retain the second and third ring members in place on the links, the links being connected one to the other along parallel axes so as to permit flexing of the mandrel in one plane only, and said links being formed to permit flexing in one direction only in said plane.

2. The tube bending mandrel recited in claim 1, in which the ends of the ring members have internal curved surfaces complementary to the external curvature of each next adjacent ring member to provide for free relative movement therebetween.

3. The mandrel recited in claim 1, in which first and third ring members have interior surfaces engageable by the first and third link means respectively to prevent separation of the assembly.

4. The tube bending mandrel recited in claim 1, in which each link has a recess on one side edge to permit displacement of the ring members in said common direction.

5. The tube bending mandrel recited in claim 1, in which the engageable means comprises a flange seated on an internal shoulder in a related ring member.

4 References Cited UNITED STATES PATENTS CHARLES W. LANHAM, Primary Examiner.

L. A. LARSON, Assistant Examiner. 

